This invention concerns improvements in or relating to fluid seals. The invention has particular, but not exclusive application to fluid seals for sealing joints between two components connected together in a fluid line, for example between two pipes, or between a pipe and another fitting or between two fittings such as a hydraulic block to which one or more parts may be attached, for example a pump or valve application.
It is already well known in the water and automotive industries to provide sealing rings for sealing joints between two components in a fluid line. The sealing rings may be made of rubber or plastics compatible with the fluid to be transmitted in the fluid line, for example water, oil, petrol, solvents.
For many applications, it is desirable to remove any solid particles present in the fluid to prevent damage to equipment connected to the fluid line. For this purpose, it is common to fit a filter in the fluid line, for example a metal or plastics mesh screen having a mesh rating to remove solid particles above a given size.
For convenience, the mesh screen may be fitted at a joint between two components in the fluid line. This can complicate the provision of an adequate seal. In addition, fitting separate seal and filter elements adds to material costs and installation costs. Also, there is a risk of joints being assembled without the filter resulting in damage to equipment connected in the fluid line.
Accordingly, the present invention seeks to provide an arrangement whereby the seal and filter are combined in a single component for installation in a fluid line.
It is a preferred object of the present invention to provide an arrangement in which a peripheral edge region of the filter is embedded in the seal, and the seal is compressible on either side of the filter between opposed surfaces of relatively axially movable components to effect a fluid tight seal between the components.
It is another preferred object of the present invention to provide an arrangement in which compression of the seal is controlled so as to maintain integrity of the seal and filter.
It is a further preferred object of the present invention to provide an assembly including an adaptor so constructed that fitment and installation of the seal and filter in a fluid line can be effected in a simple and effective manner which preferably also allows access to the filter for cleaning, repair or replacement during routine maintenance and/or in an emergency.
It is yet another preferred object of the present invention to provide such assembly in which the seal and filter are located with the filter in a desired orientation, preferably transverse, to the fluid line in which the adaptor is installed.
According to a first aspect, the present invention provides a solution to the problems and disadvantages aforementioned by providing an integral seal and filter assembly capable of sealing a joint between two components in a fluid line and filtering fluid in the fluid line. In this way, by combining the seal and filter in a single unitary construction the supply and installation of separate seal and filter elements is avoided.
The combined seal and filter can be of any size and shape to suit a given application, for example circular, oval, rectangular, or other polygonal shape. As will be appreciated, by providing an integral seal and filter, the filter can be made to any shape and the seal configured to this shape by attaching to the filter. In this way, both simple and complex seal shapes can be produced and maintained for any desired application.
Preferably, the seal is bonded to the peripheral edge of the filter. For example, the filter may comprise a mesh screen with the peripheral edge embedded in the seal. In this way, the material of the seal penetrates the interstices of the mesh so as to become mechanically bonded through the mesh.
The mesh screen may be made of metal, for example stainless steel, aluminium or brass. Alternatively, the mesh screen may be made of plastics. The mesh can be of any size for the filter rating required for a particular application.
The seal may be made of elastomer, for example rubber such as nitrite rubber, hydrogenated nitrite rubber, ethylene propylene diene monomer, fluorocarbons, polyacrylic, neoprene, fluorosilicon, or other suitable compounds for the intended application. Alternatively, the seal may be made of plastics. The seal material is chosen to be compatible with the fluid in the fluid line.
Advantageously, the mesh is provided with a barrier spaced from the peripheral edge to restrict flow of the seal material from the peripheral edge region towards the centre region of the mesh. In this way, only the peripheral edge region is embedded in the seal material and the centre region is left free to provide the filtering function.
The mesh may be woven and the barrier formed by crushing a narrow region of the mesh inwardly of the peripheral edge prior to or during moulding of the seal to form a crease separating the edge region of the mesh from the centre region to prevent the seal material penetrating the centre region of the filter. This is found to be particularly suitable for woven meshes having a mesh size of up to 200 microns.
Alternatively, the mesh may be produced by photochemical machining an array of perforations in a pre-form and the barrier formed by masking the pre-form to produce a region free from perforations separating the edge region of the mesh from the centre region to prevent the seal material penetrating the centre region of the filter. This is found to be particularly suitable for photofabrication of meshes having a mesh size of more than 200 microns, especially 300 to 400 microns.
Preferably, the seal is formed with a plurality of outwardly projecting lobes spaced apart around the outer edge of the seal and substantially co-planar with the seal and filter. The lobes facilitate moulding the seal onto the filter by allowing the seal material to pass from one side to the other around the outer edge of the filter within the mould. The lobes also act as spacers to centre the seal and filter assembly for installation in a fluid line, for example in a counterbore of a component forming part of the fluid line.
Advantageously, the seal has a sealing portion of generally trapezoidal cross-section with a maximum axial dimension at the inner edge of the seal and sealing surfaces that extend from the inner edge and converge towards each other. In this way, the inner edge of the seal has a substantially planar sectional shape in the undeformed condition of the seal and a substantially concave sectional shape when compressed. As a result, compression of the seal can be accommodated without adversely affecting the integrity of the seal and filter.
The filter provides a degree of reinforcement for the seal which is generally sufficient for most applications of the seal and filter assembly involving low fluid pressures but, at high fluid pressures, for example up to 200 bar, the seal and filter assembly is preferably provided with additional reinforcement. Such reinforcement conveniently takes the form of an outer support member, for example a plate, to which the seal is bonded to form a unitary construction.
Advantageously, the plate has a hole with a counterbore providing a shoulder for locating the peripheral edge of the filter with the seal encapsulating the peripheral edge and bonded to the marginal edge of the hole.
Preferably, the seal projects outwardly from the plate on both sides for sealing engagement with the components of the joint to be sealed. The plate may act as a spacer to limit the compression of the seal. The plate may be made of metal, for example zinc plated steel or stainless steel. Alternatively, the plate may be made of plastics, for example polycarbonate.
According to a second aspect, the present invention provides a method of forming a seal and filter assembly comprising providing a filter and bonding a seal to the marginal edge of the filter.
Preferably, the seal is confined to the marginal edge of the filter by providing the filter with a barrier prior to or during moulding of the seal onto the filter.
Advantageously, the seal is bonded to the marginal edge of a hole in an outer support member which may act as a spacer to control compression of the seal.
Preferably, the seal has a sealing portion of trapezoidal section inwardly of the hole with sealing surfaces projecting from the support member on each side and convergent from an inner edge of the seal towards the support member.
According to a third aspect, the present invention provides a method of forming a fluid tight joint between first and second components in a fluid line comprising providing an integral seal and filter element, positioning the element with the seal between opposed faces of the first and components and the filter extending across the fluid line, and relatively moving the first and second components in an axial direction to compress the seal between the opposed faces on each side of the filter.
The two components may be pipes having opposed end flanges with the seal arranged between the flanges so as to be compressed when the flanges are urged axially towards each other to provide a fluid tight joint for liquid and/or gas. One of the flanges may have a recess in the end face in which the seal is positioned to limit compression of the seal. Alternatively, one of the components may be a pipe and the other component a fitting to which the pipe is attached. Other arrangements are possible, for example a block for one or more fluid lines to which fittings are attached, for example a pump or valve, with the seal arranged between the block and the fitting.
In a preferred arrangement, the components comprise first and second threadably engageable parts of an adaptor defining a passageway for flow of fluid through the adaptor wherein the seal is disposed between opposed abutment faces of the first and second parts, and the filter is located transverse to the passageway.
According to a fourth aspect, the present invention provides an assembly for mounting in a fluid line, the assembly including an adaptor having first and second parts releasably connectable to define a passageway for flow of fluid therethrough, a filter, and a seal integral with a marginal edge of the filter, the seal being arranged to contact opposed abutment faces of the first and second parts on each side of the filter and being compressed therebetween when the first and second parts are connected to seal the filter in the adaptor with the filter extending across the passageway.
Preferably, the first and second parts have co-operating screw threads arranged for relative axial movement of the first and second parts to urge the abutment faces axially towards each other to compress the seal therebetween in the assembled adaptor. In a preferred arrangement, the first and second parts are provided with complementary internal and external screw threads on a socket portion of a female fitting and a plug portion of a male fitting.
Advantageously, one of the abutment faces is provided by the recess in which the filter and seal are located and retained in the assembled adaptor so that the filter is positioned transverse to the passageway. In this way, compression of the seal may be controlled by the depth of the recess.
Preferably, the filter and seal are mounted in a support member, such as a plate, which is received in the recess and is preferably arranged to limit compression of the seal between the abutment faces when the parts are tightened during assembly of the adaptor. For example, the depth of the recess may be less than the thickness of the support member so that the support member projects from the recess and is clamped between the abutment faces in the assembled adaptor.
Advantageously, the support member has a hole with a counterbore providing a shoulder for locating the peripheral edge of the filter with the seal encapsulating the peripheral edge and bonded to the marginal edge of the hole.
Preferably, the support member has a plurality of notches formed in the marginal edge of the hole and projecting beyond the outer edge of the filter to allow the seal material to pass around the outer edge of the filter and form a plurality of lobes spaced part around the outer edge of the seal.
Advantageously, the support, member has generally parallel upper and lower surfaces and the seal has an inner portion that projects from the upper and lower surfaces of the support member and an outer portion substantially co-planar with or set back from the upper and lower surfaces of the support member. In a preferred construction, the inner portion is of generally trapezoidal section having a wider end at the inner edge and sealing surfaces converging to a narrower end at or adjacent to the support member.
Other features, benefits and advantages of the invention will be apparent to those skilled in the art from the description hereinafter illustrating, without limitation or restriction, various aspects of the invention.